This invention relates to a filter for removing particles from a flow of dirty liquid such as machine tool coolant.
More particularly, the invention relates to a filter of the type in which a generally cylindrical drum is submerged in a tank adapted to receive the dirty liquid, the cylindrical wall of the drum being porous. When vacuum is applied to a suction line at one end of the drum, the liquid in the tank is drawn through the cylindrical wall, flows into the inside of the drum and then is discharged through the suction line.
The particles in the dirty liquid collect on the outside of the drum and form a cake which filters the liquid as the liquid passes through the drum. When the cake reaches a certain thickness and density, a portion of the cake must be scraped from the drum in order to maintain a sufficiently high flow of liquid through the drum.
A filter of this general type is disclosed in Creps et al U.S. Pat. No. 4,421,645. In that filter, the drum is rotatably mounted in the tank and is periodically indexed so that a fixed scraper adjacent the outer surface of the drum may remove a portion of the filter cake from a short arc of the drum and enable the flow through the drum to be maintained.
As explained in the Creps et al patent, it is desirable to be able to quickly disconnect the filter drum from the suction line in order that the drum may be lifted out of the tank for repair or for routine maintenance. Because the Creps et al drum both rotates relative to and is quickly disconnectable from the suction line, rather special and elaborate provisions must be made in order to maintain a liquid-tight seal between the drum and the suction line.